Paper mills and lumber mills are typically located in central locations with respect to the availability of resources, such as water, power, and forest resources, and access to major transportation routes for both receiving raw materials and for shipment of finished products. The demand for wood often requires the geographic area from which a particular mill draws its requirements to be quite large. Hauling distances from mills in excess of 100 to 200 miles are not unusual. Such substantial hauling distances increase transportation costs, to the point that they become a substantial factor in the overall cost of the raw materials.
The transportation method most widely used in the forest products industry for relatively short distances is truck transportation. Truck transportation is suitable for hauling logs from the harvest site to the mills over distances of less than about 100 miles. As the distance increases beyond 100 miles, the cost of truck transportation becomes prohibitive. Truck transportation is also dependent on a good highway transportation system and can be severely restricted in certain areas due to traffic from urban and suburban development.
Beyond the practical and economical range of truck transportation, timber is generally transferred to rail for shipment. Rail transportation is economical for essentially all distances, but is particularly advantageous from a cost standpoint for long-haul areas, i.e., areas in excess of 100 miles from the mill site. Over such distances, rail is three to four times as efficient as truck transportation. Where rail transportation is employed, timber is transported short distances to a railhead and shipped to a mill for use. Rail transportation would be more widely used, except for certain shortcomings that have been encountered with respect to the railcars that have been employed to transport logs to the mill.
For various reasons, it is sometimes desirable to ship logs in a form known as "tree-length" timber which, as the name implies, are logs which are substantially the length of the tree from which they have been cut and de-branched. Typically, tree-length timber is from about 30 feet to about 50 feet in overall length. Because the longest tree-length timber is longer than about one-half the length of typical existing railcars, and since most mills cannot accept tree-length wood that is randomly oriented, it is the usual practice to load and unload this timber in two or more "decks" each deck being substantially wedge-shaped because the logs taper, that is, the diameter of the log at what was the base of the tree is larger than the other end. As a result, the load typically comprises two wedge-shaped decks with the tip ends overlapping one another. Another preferred form in which timber is shipped is in the form of "long logs" about 15-20 feet in length. Because of their shorter length, long logs may be readily placed in two or more spaced-apart stacks on the bed of the railcar. The shorter length of long logs also reduces the degree of taper encountered, and they are generally oriented randomly, resulting in stacks which are substantially "square". Because long logs are 15 to 20 feet in length, they cannot be stacked crossways on a railcar, since the maximum width of the railcar is between 10 feet, 6 inches and 10 feet, 8 inches.
Tree-length logs are the most preferred method of receiving wood at the mills, as they provide for the maximum utilization of the wood at the lowest cost. When tree-length logs are received by a mill, particularly one which is associated with a lumber operation, the economic yield from the wood is greater than with either wood chips, short wood or long logs. The tree-length logs can be sorted at the mill into logs suitable for conversion into lumber or plywood, and the less suitable logs can then be used in papermaking processes. Furthermore, the processing of tree-length logs at paper mills which have appropriate equipment, such as slasher decks to cut the logs into predetermined lengths, is considerably less expensive than cutting tree-length logs into shorter lengths or chips at the harvesting site because of the more efficient equipment and better material handling methods available at the mill site.
Thus, for example, in pulping operations employed in the making of paper and other products, it is preferable to use tree-length logs to minimize the expense related to the cutting and handling of the timber. Although the shorter long logs are frequently used, they are less well suited to pulping operations. In the pulp industry, it is thus currently the practice to utilize tractor trailers to haul both tree-length timber and long logs to pulping mills. However, the impracticality of bringing a fleet of trucks to remote logging areas, as well as the delays encountered due to highway conditions and traffic, result in a nearly unmanageable situation. Accordingly, there exists a need to provide a convenient and efficient way to ship both tree-length timber as well as long logs via rail.
Numerous railcars have been specifically designed to meet the needs of the timber industry such as railcars specifically adapted to carry tree-length timber. However, because of the simpler loading configuration, the bulk of the railcars designed for hauling logs used in North America are adapted to carry long logs. As shown in the Car and Locomotive Cyclopedia, compiled and edited for the Association of American Railroads (Simmons-Boardman Pub. 1974), numerous designs for log hauling are shown in the section designated "Flat Cars" at pp. S3-161 S-168. Particularly at page S3-162, a log car built for Burlington Northern is shown. The Burlington Northern Log Car has a center sill, outer sills and an open floor, together with side supports for the logs. Numerous other flat car designs having flat floors and bulkheads disposed at either longitudinal end are also shown in the same reference.
U.S Pat. No. 934,906 (Frame et al.) discloses a railcar adapted for transporting logs having a longitudinally extending central member or "sill" extending the length of the railcar and a pair of bolsters oriented transversely and attached to the sill near either end of the sill. U.S. Pat. No. 711,271 (Ashcraft et al.) also discloses a railcar adapted to carry logs. The railcars disclosed by Frame et al. and Ashcraft et al., however, are essentially "skeleton" flat cars, wherein the logs are stacked lengthwise and retained by a chain extending over the stack. Others have found that when hauling logs, it will be desirable to provide vertical standards or stanchions, attached to the distal ends of the transverse bolsters, such as the log carrier disclosed in U.S. Pat. No. 405,819 (Billings) and the railcar disclosed in U.S. Pat. No. 1,799,628 (Enowles).
U.S. Pat. No. 930,623 (Shillin) discloses the use of stakes attached to logging cars to retain logs in position during transportation. Also disclosed are means for locking the stakes in position during transit and means for releasing the locking means to permit repositioning of the stakes, thereby allowing discharges of the logs from either side of the car.
U.S. Pat. No. 4,624,188 (Kaleta) discloses bulkheads with fixed side and end container restraining walls with moveable corner engaging mechanisms to selectively restrain either a short or a long container supported upon a lower container in transport position.
The problems which have been encountered using such prior art designs are to a large extent a result of the inherent tapered shape of tree-length logs. The butt end of the logs, that is, the end that was at the root of the tree, is always larger than the tip end of the log. Furthermore, the individual logs may be somewhat twisted, which is not conducive to uniform stacking. The problem of instability of the stacks of logs on the railcars is further complicated by the requirements of the mills that the stacks of tree-length logs be aligned with all the butt ends at one end of a given stack so as to facilitate the unloading and handling of the logs at the mills. It is this practice that leads to loading the railcars with wedge-shaped "decks" of tree-length logs. It has been found, however, that such decks are inherently unstable in transit. The logs in the decks readily break loose or are repositioned so as to cause potential serious problems and personal injury. In transit, railcars are regularly subjected to impact as a result of starting and stopping that can have a force of several miles an hour. Impact at speeds as low as 5 miles per hour can cause a deck of logs to shift in position. Furthermore, when the railcars are struck, the wedge configuration often causes one or more of the individual tree-length logs within the wedge to slide forward out of the deck. As the individual logs start to slide forward, the entire deck becomes unstable. The individual logs are often ultimately forced from the decks, where they can either fall onto the tracks, causing serious safety problems, or project from the side of the railcars to contact and damage trains, cargo, and injure personnel on adjacent trains and tracks.
Other problems similar to those described above have been encountered when hauling tree-length logs. One such problem is that when the logs are transported in decks they tend to become entangled with each other. When the logs arrive at the mill it then becomes very difficult, if not impossible, to unload them in bulk from the railcars, thus substantially increasing the amount of time required for unloading and handling of the logs. A related problem is that the railcars utilized for hauling of tree-length logs must be exceptionally durable and rugged, but also should be as light in weight as possible. In use, railcars used for hauling tree-length logs must be able to endure the day-in, day-out abuse encountered in both the loading and unloading of the logs. While the durability of the cars can be increased by using heavier weight members and increasing the reinforcement, as is conventional with other types of cars, increased weight presents problems, in that there is a maximum weight allowable for railcars and their loads that can be transported on existing rails. Tree-length logs are an exceptionally heavy cargo and, accordingly, increasing the strength by using heavier weight members and additional reinforcement directly reduces the effective payload of the logs which can be handled.
It would therefore be highly advantageous to provide a railcar suitable for safe handling of tree-length logs which can easily be loaded and off-loaded, and which is strong enough to endure the rough handling encountered in normal use. Additionally, it would be desirable to design such a railcar that could also readily transport long logs.